In 1776, about five years after his call to the bar, Wilmot was returned to parliament for Tiverton in Devon; and, taking part with the opposition, attacked the ministerial party in a pamphlet, denouncing the continuance of the American Revolutionary War. In 1781, he was appointed a master in Chancery; and, in 1782, was commissioned, in conjunction with others, to inquire into the distribution of the sums destined for the relief of the American loyalists. In the following year, he spoke on the subject in parliament; and, in reply to Charles James Fox's condemnation of the large sums expended on the American sufferers, he declared "he would share with them his last shilling and his last loaf."

In 1784, and the parliament which followed in 1790, Wilmot sat as member for Coventry, and supported the views of Pitt during every session. He was hostile to the French revolution and obtained the distribution of a fund, under the sanction of parliament, on behalf of the emigrants from that country. He was the author of A Treatise on the Laws and Customs of England.

In 1804, Wilmot retired from public life and devoted himself to writing. He published a Life of his father and another of Bishop Hough. In the year of his death, 1815, An Historical Review of the Commission relative to the American Loyalists appeared.

He was reported to be a man of upright and unimpeachable character, learned and eloquent. He was twice married. His first wife was the only daughter of S. Sainthell, Esq., by whom he had one son, Sir John Eardley-Wilmot, 1st Baronet, and four daughters. He married secondly, in 1793, Miss Hastam, by whom he had two further children who both died young.